diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index c93089330030f07a42bd38502c4a536ffec75447..f72b80c70484062e92fe9ff3df6fb8b951f70e61 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -1334,7 +1334,7 @@ static int sd_set_card_speed(struct mmc *mmc, enum bus_mode mode)
 	return 0;
 }
 
-int sd_select_bus_width(struct mmc *mmc, int w)
+static int sd_select_bus_width(struct mmc *mmc, int w)
 {
 	int err;
 	struct mmc_cmd cmd;